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Author Topic:   Mt. St. Helens
faith24
Junior Member (Idle past 1639 days)
Posts: 27
Joined: 09-10-2010


Message 1 of 16 (595896)
12-11-2010 2:28 AM


I have some general questions about Mt. St. Helens, I find it quite interesting to get educated in this area. I'm not a geologist so please forgive me if I misrepresent something.

After Mt. St. Helens erupted it formed sedimentary layers that were pyroclast. The mudflow deposited were 2 years after. I'm curious what distinguished slow canyons from fast canyons such as the Grand Canyon? This will be my main question, but I'll ask more questions after this thread has been approved by Admin.


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Message 2 of 16 (595910)
12-11-2010 8:32 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Mt. St. Helens thread in the Proposed New Topics forum.
    
jar
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Message 3 of 16 (595968)
12-11-2010 4:27 PM


I suggest that you start by looking at Looking at the Grand Canyon from the bottom up.


Anyone so limited that they can only spell a word one way is severely handicapped!
  
Dr Adequate
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Message 4 of 16 (595981)
12-11-2010 8:31 PM
Reply to: Message 1 by faith24
12-11-2010 2:28 AM


After Mt. St. Helens erupted it formed sedimentary layers that were pyroclast. The mudflow deposited were 2 years after. I'm curious what distinguished slow canyons from fast canyons such as the Grand Canyon?

(1) I don't know why you call the Grand Canyon "fast". Did you mean to write that the other way round?

(2) You should distinguish between the formation of the rocks and the formation of the canyon.

(3) The rocks of the Grand Canyon are formed from different materials. Geologist can tell the difference between volcanic ash and tuff and (e.g.) marine limestone, you know. Where they find layers of volcanic ash, naturally they attribute them to the action of volcanoes.


This message is a reply to:
 Message 1 by faith24, posted 12-11-2010 2:28 AM faith24 has responded

Replies to this message:
 Message 5 by faith24, posted 12-11-2010 11:42 PM Dr Adequate has responded

  
faith24
Junior Member (Idle past 1639 days)
Posts: 27
Joined: 09-10-2010


Message 5 of 16 (595991)
12-11-2010 11:42 PM
Reply to: Message 4 by Dr Adequate
12-11-2010 8:31 PM


quote:
(1) I don't know why you call the Grand Canyon "fast". Did you mean to write that the other way round?

Yes.

quote:
(3) The rocks of the Grand Canyon are formed from different materials. Geologist can tell the difference between volcanic ash and tuff and (e.g.) marine limestone, you know. Where they find layers of volcanic ash, naturally they attribute them to the action of volcanoes.

From what I understand after Mt. St. Erupted, the volcanic ashes and particles did formed sedimentary layers, so both things are true. However, they are different I guess? But regarding the Grand Canyon they may have been unconsolidated as there are slump at the very bottom, right? Does Mt. St. Helens show that sedimentary layer can form rapidly, because they're volcanic lava and particles, but not rocks? So rocks takes longer?


This message is a reply to:
 Message 4 by Dr Adequate, posted 12-11-2010 8:31 PM Dr Adequate has responded

Replies to this message:
 Message 6 by Coyote, posted 12-12-2010 12:12 AM faith24 has responded
 Message 7 by Dr Adequate, posted 12-12-2010 12:14 AM faith24 has responded

    
Coyote
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Message 6 of 16 (595992)
12-12-2010 12:12 AM
Reply to: Message 5 by faith24
12-11-2010 11:42 PM


Mt. St. Helens is a piker
Rock layers can be dated, and their depositional history can be determined. This can be done using a number of different techniques which complement one another.

Mt. St. Helens deposited a lot of material, but the material in the river beds is not rock. Rock takes a long time to form. What St. Helens deposited in the lower valleys is still more akin to mud -- sediments. It washes downhill very easily and accumulates in the valleys. This is very different from the lava flows that you see from various volcanoes.

Erosion can cut through mud very quickly, but that says nothing about the rate of erosion in rock layers. That takes a long time, depending on a wide variety of factors.

For creationists to try to equate the two, mud vs. rock (St. Helens vs. the Grand Canyon), is neither accurate nor honest.

Why can't you folks just stick to the facts?


Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
This message is a reply to:
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Dr Adequate
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Posts: 16097
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Message 7 of 16 (595993)
12-12-2010 12:14 AM
Reply to: Message 5 by faith24
12-11-2010 11:42 PM


From what I understand after Mt. St. Erupted, the volcanic ashes and particles did formed sedimentary layers ...

Well, sort of sedimentary. Geologists joke that volcanic ash is "igneous when it goes up and sedimentary when it comes down". (I didn't say it was a funny joke.)

... But regarding the Grand Canyon they may have been unconsolidated as there are slump at the very bottom, right?

I'm not following you, sorry.

Does Mt. St. Helens show that sedimentary layer can form rapidly, because they're volcanic lava and particles, but not rocks? So rocks takes longer?

It depends on what you mean, and on the rock.

Volcanic ash can form rock almost immediately if it's hot enough when it falls to weld itself together; this gives us the rock known as "welded tuff". Or it can be slowly cemented together by the usual process that also cememts together such things as sandstone, which takes longer.

There are other processes besides volcanism that deposit a relatively thick layer of sediment quickly, such as turbidity currents. That then takes a long time to turn into rock (turbidite).

A layer of basaltic lava can be extruded quite quickly and will be baslat as soon as it cools.

Other things, such as limestone or chert are deposited very slowly and then take a long time to be compacted into rock.

So how long it takes for (a) the original material to be deposited and (b) for the material to be lithified (turned into rock) depends on what sort of rock it is.

If you look at this page and follow links 2-13 where it says "Related articles" you can find out about various sorts of sedimentary rocks and the circumstances under which they're deposited and how we know this.


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 Message 5 by faith24, posted 12-11-2010 11:42 PM faith24 has responded

Replies to this message:
 Message 8 by faith24, posted 12-12-2010 2:57 AM Dr Adequate has responded

  
faith24
Junior Member (Idle past 1639 days)
Posts: 27
Joined: 09-10-2010


Message 8 of 16 (596002)
12-12-2010 2:57 AM
Reply to: Message 7 by Dr Adequate
12-12-2010 12:14 AM


Thanks, but the links does not work.
This message is a reply to:
 Message 7 by Dr Adequate, posted 12-12-2010 12:14 AM Dr Adequate has responded

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 Message 10 by Dr Adequate, posted 12-12-2010 3:06 AM faith24 has responded

    
faith24
Junior Member (Idle past 1639 days)
Posts: 27
Joined: 09-10-2010


Message 9 of 16 (596003)
12-12-2010 3:05 AM
Reply to: Message 6 by Coyote
12-12-2010 12:12 AM


Re: Mt. St. Helens is a piker
quote:
For creationists to try to equate the two, mud vs. rock (St. Helens vs. the Grand Canyon), is neither accurate nor honest.

Why can't you folks just stick to the facts?


So what you're saying is that Mt. St. Helens made the layers/canyons quicker, but the Grand Canyon is rock so it takes long periods of time, is that correct?

The Grand Canyon is rock and hardened now, but it may not have been when it was carved.


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Dr Adequate
Member
Posts: 16097
Joined: 07-20-2006


Message 10 of 16 (596004)
12-12-2010 3:06 AM
Reply to: Message 8 by faith24
12-12-2010 2:57 AM


Thanks, but the links does not work.

The hosting provider, a company called "Wiredtree" has been having technical difficulties. It should be working again soon-ish.

I wrote the articles myself, and I think they're particularly useful because they repeatedly ask and answer the question "how do we know this?" rather than just treating the subject as information handed down from on high by the Grand Exalted Wizards Of Geology.

Edited by Dr Adequate, : No reason given.


This message is a reply to:
 Message 8 by faith24, posted 12-12-2010 2:57 AM faith24 has responded

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faith24
Junior Member (Idle past 1639 days)
Posts: 27
Joined: 09-10-2010


Message 11 of 16 (596005)
12-12-2010 3:22 AM
Reply to: Message 10 by Dr Adequate
12-12-2010 3:06 AM


Thanks, I will check on it.
This message is a reply to:
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Dr Adequate
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Posts: 16097
Joined: 07-20-2006


(1)
Message 12 of 16 (596006)
12-12-2010 3:28 AM
Reply to: Message 9 by faith24
12-12-2010 3:05 AM


Re: Mt. St. Helens is a piker
There are a few points to ponder here.

First, the rocks at the bottom of the Grand Canyon are not sedimentary, they're metamorphic and igneous.

Second, look at the cross-section.

If the canyon was cut through fresh sediment, is there any way that the wet sand, the mud, and the calcareous ooze wouldn't have slumped forward and downward? Look at the limestone layers. Is there any way you could cut a near-vertical wall in calcareous ooze? If you could, is there any way it wouldn't have squidged out under pressure like toothpaste from a tube?

Also, if you're thinking of some sort of YEC "flood geology" model, that means that all that unlithified sediment turned into rock ... how fast?

You might also like to have a think about how the angular unconformity was formed.

Edited by Dr Adequate, : No reason given.


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 Message 9 by faith24, posted 12-12-2010 3:05 AM faith24 has not yet responded

  
jar
Member
Posts: 31065
From: Texas!!
Joined: 04-20-2004
Member Rating: 3.6


Message 13 of 16 (596014)
12-12-2010 11:07 AM
Reply to: Message 9 by faith24
12-12-2010 3:05 AM


Re: Mt. St. Helens is a piker
The Grand Canyon is rock and hardened now, but it may not have been when it was carved.

Of course not.

Did you read the thread I provided?

Do you understand the lowest exposed layer of the Grand Canyon is schist?


Anyone so limited that they can only spell a word one way is severely handicapped!
This message is a reply to:
 Message 9 by faith24, posted 12-12-2010 3:05 AM faith24 has not yet responded

  
JonF
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Posts: 5011
Joined: 06-23-2003
Member Rating: 3.3


Message 14 of 16 (596020)
12-12-2010 11:38 AM


One thing that hasn't been mentioned (and faith24 does not seem to know) is that the walls of "canyons" carved in mud or soft sediment form relatively shallow-angle walls (on the order of 45 degrees), while canyons carved on solidified rock have relative steep walls (often on the order of 90 degrees from horizontal).

The Toutle River at Mt. Saint Helens in 1983:

In 1985:

(both from Mount St. Helens, Washington: 1980 Debris Avalanche: 1980-Current, part of Mount St. Helens, Washington: Photo Archives.)

The Grand Canyon walls are generally pretty vertical (except for landslides) as shown by the photos already presented, but just to be complete here's the Vishnu Temple:

Another important point is that meanders are only formed by relatively slow-moving water. There are no meanders in the Toutle River "canyon", but just upstream of the Grand Canyon, the Goosenecks:

and Horseshoe Bend:

Note the near-vertical walls.

So we conclude that the Grand Canyon was carved in hard rock by a river moving much slower than the Mt. Saint Helens devbris avalanche.


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Dr Adequate
Member
Posts: 16097
Joined: 07-20-2006


Message 15 of 16 (596055)
12-12-2010 4:06 PM
Reply to: Message 14 by JonF
12-12-2010 11:38 AM


One thing that hasn't been mentioned (and faith24 does not seem to know) is that the walls of "canyons" carved in mud or soft sediment form relatively shallow-angle walls (on the order of 45 degrees), while canyons carved on solidified rock have relative steep walls (often on the order of 90 degrees from horizontal).

Well I think I alluded to it, but it's nice to see pictures.

So that is the famous creationist "canyon" at Mt. St. Helens?

It looks just as I imagined it.


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